Composition of matter and process of preparing the same



Patented Feb. 6, 1934 COMPOSITION OF MATTER AND PROCESS OF PREPARING THE SAME Edmund 0. Rhodes and Elmer H. Hyde, Pittsburgh, Pa., assignors to American Tar Products Company, Inc., a corporation of Delaware No Drawing. Application July 10, 1931 Serial No. 550,040

15 Claims.

This invention relates to compositions of rratter and processes of preparing the same, and more particularly to compositions of a pitchy nature employed in binding materials.

Pitch-containing materials are commonly used as temporary binders in the manufacture of carbon electrodes, carbon blocks, carbon brushes, fuel briquettes, etc. Finely ground carbon and other ingredients are mixed with pitch and formed into the desired shape. The molded product is baked, during the course of which process the volatile matter of the pitch is driven off and a permanently binding coke residue is left to form thereby a solid compact mass. Pitches ordinarily employed for these purposes are commonly prepared by distilling coal tar until a residue of the required melting point is obtained.

An object of the present invention is to provide an improved binder having a number of desirable characteristics when used in the manufacture of carbon electrodes and similar products.

The binder which is the product of the present invention comprises a mixture of certain of the higher boiling constituents obtained in the distillation of tars such as coal tars, gas-house coal tars, coke-oven tars, vertical retort tars, low temperature tars, oil tars, oil gas tars, water-gas tars or mixtures of any or all of such tars. An essential ingredient of the composition is a distillate, which when distilled, boils above substantially 300 C. and preferably above 350 C. Preferably a distillate is used which is obtained when pitches from the aforesaid tars or mixtures thereof, are heated to form coke.

The condensate of vapors obtained in the coking of pitch is designated by the term pitch oil. This pitch oil is the condensate of the vapors formed when pitch is distilled to coke either in metal stills, refractory ovens, or in by-product coke ovens, as described in application Serial No. 338,644, filed February 9, 1929, or in application Serial No. 500,540, filed December 6, 1930, by E. O. Rhodes, and in U. S. Patent No. 1,715,240 to H. Koppers.

The pitch oil may be obtained from the coking of either soft or hard pitches. In certain instances the pitch oil obtained in the baking of electrodes or similar products may also be employed.

In the preparation of the binder a mixture of pitch oil and tar such as those mentioned is heated to remove the lower boiling constituents. For instance. about parts by weight of coal tar obtained from either high or low temperature coking processes, and about 35 parts by weight of pitch oil are mixed together and distilled until a residue is obtained having a melting point in accordance with the cube-in-air method, of substantially 30 C. to 160 C. or preferably 85 C. to 110 C.

Another method of preparing a binder is by distilling tar to obtain a residue of hard pitch having a melting point of substantially 100 C. to 150 C. or preferably about 150 C., or at least a melting point above that desired in the finished product. Pitch oil is then added to the molten hard pitch.

The differences between the pitches made by straight distillation of coal tar and the pitches made from our coal tar and pitch oil mixtures are made quite evident in the following table, which compares results of the distillation of pitches of substantially the same melting point and prepared by the former and latter methods. The distillations were made in an E-l flask according to the method described in A. S. T. M. test D-20--.30 on page 642 of part II of the 1930 edition of the Triennial Standards of the American Society for Testing Materials.

Pittciihy Pitchy Coal tar ma er Coal tar matter from coal from coal pltch tar and pltch tar and pitch-oil pitch-oil Melting point 88.?" C. 87.5 0. 111 C. 109 0.. First drop ofdistillate. 335 0. 356 0. 350 0. 339 C. distillate by wt. up to 73g5?1 -i; t-....i 2.7 0.0 0.6 0.5

a isti ate y w p 0 370 C 5.9 1.1 2.9 0,7 distillate by wt p to 385 C 11.2 2.4 8.3 1.1 distillate by wt. up to 396 C 15. 5 4. 2 13. 8 1. 8 distillate by wt. up to 400 C l9. 8 7. 1 l8. 5 4. 5 residue by weight at The binder of the present invention comprises bituminous matter which evolves a smaller total quantity of vapors when heated to 400 C. or even to baking temperatures around 1000 C. than pitch having substantially the same melting point. This is true whether the rate of rise in temperature is high or low.

In baking electrodes, for instance, the rate of rise in temperature is about three to eight degrees centigrade per hour and usually six degrees. For the same rate of rise in temperature. vapors are evolved from our binder at a slower rate than from pitch having substantially the same melting point. When using the binder of the present invention, a baking operation can therefore be speeded up considerably with safety, that is, without danger of breaking the molded products treated.

When our binder is carbonized under conditions simulating the baking of electrodes for instance, a much greater coke residue is obtained containing a greater amount of binding constituents than when ordinary pitch of similar melting point is carbonized under the same conditions. The finished electrodes are denser and stronger when our binder is employed even in smaller amounts than ordinary pitch.

In the preparation of our binder we may substitute for pitch oil, an extremely heavy distillate, as for instance heavy creosote from which 0% up to substantially 9% distills off at 355 C. Pitch oil is preferred however and best results are obtained therewith.

We claim as our invention:

1. A binding material comprising pitch and a material consisting of a mixture of high-boiling constituents from the condensate of vapors obtained in coking pitch.

2. A binding material comprising hard pitch from tar and a material consisting of the condensate of vapors obtained in coking pitch.

3. A binding material comprising pitch having a melting point of substantially 100 C. to 150 C., and a material consisting of the condensate of vapors obtained in coking pitch.

4. A binding material comprising pitch having a melting point of substantially 150 C. and a material consisting of the distillate obtained in coking pitch, which distillate boils above substantially 300 C.

5. A binding material comprising a mixture of pitch and a material consisting of a mixture of high-boiling constituents from the condensate of vapors obtained in'coking pitch, the said mixture having a melting point of substantially 30 C. to 160 C.

6. A binding material'comprising a mixture of pitch having a melting point of substantially 150 C. and a material consisting of the condensate of vapors obtained in coking pitch, the said mixture having a melting point of substantially 30 C. to 160 C.

'7. A process of preparing a binding material which process comprises heating together constituents of tar and the condensate of vapors obtained in coking pitch, to form a pitchy mixture having a melting point of substantially from 30 C. to 160 C.

8. A process of preparing a binding material which process comprises mixing tar with a condensate of vapors obtained in coking pitch, heating the resulting mixture to vaporize the lower boiling constituents and removing the said lower boiling constituents to form a residue having a melting point of substantially from 30 C. to 160 C.

9. A binding material comprising a mixture of pitch and a material consisting of the condensate of vapors obtained in coking pitch, which mixture on heating the same to substantially 400 C. yields a residue containing a greater amount of, binding constituents than when ordinary pitch of substantially the same melting point as the said mixture, is heated to substantially the same temperature.

10. A binder for carbon materials comprising bituminous matter containing material consisting of the condensate of vapors obtained in coking pitch, which bituminous matter evolves a smaller total quantity of vapors when distilled up to 400 C. than pitch evolves under the same conditions and having substantially the same melting point as the said bituminous matter.

11. A binder for carbon materials comprising bituminous matter containing material consisting of the condensate of vapors obtained in coking pitch, which bituminous matter when heated evolves vapors at a substantially slower rate for a given rate of rise intemperature than pitch having substantially the same melting point as the said bituminous matter.

12. A binding material comprising a mixture of coal tar pitch, and heavy distillate from which 0% up to substantially 9% distills off when heated to 355 C., the said mixture having a melting point of substantially 30 C. to 160 C.

13. A binding material comprising a mixture of pitch having a melting point of substantially 100 to 150 C., and pitch oil obtained as a distillate in coking pitch, the said mixture having a melting point of substantially 30 C. to 160 C.

14. A binding material comprising a mixture of pitch having a melting point of substantially 150 C. and pitch oil obtained as a distillate in coking pitch, the said mixture having a melting point of substantially 85 C. to 110 C.

15. A binding material comprising a mixture of pitch having a melting point of substantially 100 C. to 150 C., and pitch oil obtained as a distillate in coking pitch, the said mixture having a melting point of substantially 85 C. to 110 C.

ELMER H. HYDE. 

